Logging in to an FTP server is similar to logging into any website. Certain information is required; a server address or URL, plus an authorized user name and password. Here's an example:
site:ftp.notarealsite.com
login:user9000
pass:f4k3Pw
The first line in the example is the address of the FTP server, which is not always exactly the same as the public URL, and often contains "ftp", but not always. Your server administrator will provide that information, usually in site documentation. The login name and password are pretty self-explanatory, but they have to be set up in advance. You will not be able to create a user to log into a server. For security purposes, the system administrator must do this.